I'm not an expert, but as a (former) drone enthusiast, it's probably because of C values. C values tell you how quickly a battery can be safely discharged, and

I'm not an expert, but as a (former) drone enthusiast, it's probably because of C values. C values tell you how quickly a battery can be safely discharged, and it's based on the amperage. Specifically, it's a direct multiplier for the amperage. And for batteries in the before times, the voltage was clearly printed on the battery, as was the mAh and C values.